Impact of polydimethylsiloxanes on physicochemical and tribological properties of naphthenic mineral oil(KN 4010)-based titanium complex grease

Titanium complex greases were prepared by using naphthenic mineral oil and polydimethylsiloxane as the mixed base oil. The effect of polydimethylsiloxane molecular weight and polydimethylsiloxane content in mixed base oil on the physicochemical and tribological properties of titanium complex greases was investigated.As compared to the sole mineral oil-based titanium complex grease, the use of polydimethylsiloxane(H201-350)as a co-base oil increased the dropping point from 310 to 329℃, decreased the oil separation from 3.7% to 2.3%,reduced the corrosion extent, and obviously improved the tribological properties. When the mixed oil-based titanium complex grease was used as a lubricant, lubricating films of polydimethylsiloxane were probably formed on the surfaces of friction pairs, giving good lubricating property.

Discussion on the Mechanism of Boric Acid and Phosphoric Acid to Improve the Hardening of Complex Calcium Lubricating Grease

In order to solve the hardening problem of complex calcium lubricating grease, the water absorption test of several calcium salts was carried out, and it was found that calcium 12-hydroxystearate did not absorb water, and calcium acetate, calcium phosphate and calcium borate had different degrees of water absorption. Calcium acetate has the highest water absorption rate, while calcium phosphate and calcium borate show comparable water absorption rates. Upon using the molecular simulation technology, it is found that in the complex calcium grease system, calcium phosphate and calcium borate tend to combine with water, which inhibits the water absorption of calcium acetate and alleviate the hardening problem.

Preparation of hyperthermal lithium complex grease

Using 12-hydroxystearate, nonan-edioic acid and lithium hydroxide as thickener, refined mineral oil and synthetic oil as base oil, along with some structure improver, antioxidant and anti-wear extreme pressure additive, lithium complex grease was developed. The dropping point of the grease is 331℃, friction factor is 0.0250.026 under 1.0kN, especially above 220℃, its friction factor is 2/3 of those of urea-based greases and other high temperature greases. At the same time, it has good waterproof, anti-oxidation effect and anti-corrosion properties. The results of the field experiment proves that its working temperature is higher than 600℃, and it has reasonable working life in 800℃.

Well-Dispersed Graphene Enhanced Lithium Complex Grease Toward High-Efcient Lubrication

Graphene as a lubricating additive holds great potential for industrial lubrication. However, its poor dispersity and compatibility with base oils and grease hinder maximizing performance. Here, the infuence of graphene dispersion on the thickening efect and lubrication function is considered. A well-dispersed lubricant additive was obtained via trihexyl tetradecyl phosphonium bis(2-ethylhexyl) phosphate modifed graphene ([P_(66614)][DEHP]-G). Then lithium complex grease was prepared by saponifcation with 12-OH stearic acid, sebacic acid, and lithium hydroxide, using polyalphaolefn (PAO20) as base oil and the modifed-graphene as lubricating additive, with the original graphene as a comparison. The physicochemical properties and lubrication performance of the as-prepared greases were evaluated in detail. The results show that the as-prepared greases have high dropping point and colloidal stability. Furthermore, modifed-graphene lithium complex grease ofered the best friction reduction and anti-wear abilities, manifesting the reduction of friction coefcient and wear volume up to 18.84% and 67.34%, respectively. With base oil overfow and afux, well-dispersed [P_(66614)][DEHP]-G was readily adsorbed to the worn surfaces, resulting in the formation of a continuous and dense graphene deposition flm. The synergy of deposited graphene-flm, spilled oil, and adhesive grease greatly improves the lubrication function of grease. This research paves the way for modulating high-performance lithium complex grease to reduce the friction and wear of movable machinery.

Preparation of Overbased Calcium Alkylbenzene Sulfonate for Formulating Complex Sulfonate Grease

Six kinds of alkylbenzene sulfonic acids were selected to prepare the sulfonates S1—S6. Among them, the sulfonates S3, S4, and S6 could be incorporated into lubricating grease with good performance in comparison with the grease produced from commercial sulfonates T106-1 and T106-2. The optimized conditions for synthesis of the sulfonates S3, S4, and S6 were explored by using different mass ratios of methanol, water and the type of copromoters. It was found out that the appropriate conditions for synthesis of the sulfonate S3 included a methanol to M(M is the total mass of alkylbenzene sulfonic acid and base oil) mass ratio of 16%, a water to M mass ratio of 4%, and a copromoter A to M mass ratio of 2%; the appropriate conditions for synthesis of the sulfonate S4 included a methanol to M mass ratio of 24%, a water to M mass ratio of 2%, a copromoter B to M mass ratio of 2%; and the optimized conditions for synthesis of the sulfonate S6 included a methanol/ M mass ratio of 8%, a water/M mass ratio of 4% and a copromoter B/M mass ratio of 2%. The new sulfonates S3, S4, and S6 produced under the optimized conditions exhibited higher TBN and better antiwear property in camparison with the previous products. Grease samples G9, G10, and G11 were prepared with new sulfonates S3, S4, and S6 successfully and exhibited improved water stability and high temperature performance.

Tribological and rheological performance of lithium grease with poly-a-olefin and alkyl-tetralin as base oils

A new category of lithium greases was synthesized by using poly-a-olefin(PAO8) and alkyl-tetralin as base oil, where the alkyl-tetralins were synthesized by the alkylation of tetralin and olefins. The influence of thickener concentration, alkyl-tetralin content and type of blend oils on the rheological and tribological performance of lithium grease was investigated. The microstructures of soap fibers were measured to reveal the structure-property correlations. The concentration of thickener and alkyl-tetralin content obviously affect the lubricating performance of lithium grease, while the molecular structure of alkyltetralin has no obvious impact on their properties. It was found that alkyl-tetralin could significantly enhance the thickening ability of PAO8 base oils, and decrease the amount of thickeners by 1.5%(mass).Lithium greases prepared using 20%(mass) alkyl-tetralin as co-base oil exhibited high colloidal stability,excellent rheological behaviors and tribological properties.

不同有机酸配比对复合钛基润滑脂性能的影响规律

采用苯甲酸、硬脂酸、钛酸异丙酯和环烷基矿物油4016为原料,通过改变硬脂酸和苯甲酸2种有机酸的比例制备了复合钛基润滑脂,系统的研究了其理化性能、流变学性能和摩擦学性能.流变学试验结果表明:增大硬脂酸比例,可以提高润滑脂的结构强度.当硬脂酸与苯甲酸摩尔比为2:1(TCG3)时,样品的屈服应力达到最大值2530 Pa.摩擦学试验结果表明:当硬脂酸与苯甲酸摩尔比为1:1(TCG4)时,所制备的复合钛基润滑脂具有最佳的摩擦学性能,平均摩擦系数为0.089,磨斑直径为0.57 mm,最大无卡咬负荷(PB)值为490 N,摩擦学性能明显优于复合锂基润滑脂KK-311(平均摩擦系数为0.108,磨斑直径为0.81 mm,最大无卡咬负荷为98 N).说明TCG4不仅具有优异的减摩抗磨性能,而且具有良好的承载能力.综合上述结果,通过改变硬脂酸和苯甲酸的摩尔比例获得了结构强度高和摩擦学性能优的复合钛基润滑脂产品,表明可以通过改变有机酸的比例优化复合钛基润滑脂的综合性能,为高性能复合钛基润滑脂的结构调控和基础性能研究提供技术支持,促进其在润滑工程领域的应用.

纳米二氧化铈添加剂对复合锂基润滑脂摩擦学性能影响研究

为进一步提高复合锂基润滑脂摩擦学性能,将不同质量分数的纳米氧化铈(nano-CeO_(2))粒子添加到复合锂基润滑脂中,并利用四球摩擦磨损试验机对所制备的复合锂基润滑脂摩擦学性能进行测试,分析摩擦系数变化趋势.利用扫描电镜(SEM)、倒置金相显微镜和三维表面形貌仪观察摩擦试验后钢球表面磨痕形貌变化,并测量磨斑直径大小,同时使用X射线光电子能谱(XPS)和能谱仪(EDS)对润滑脂以及钢球表面典型元素变化情况进行测试,分析纳米氧化铈对润滑脂摩擦学性能影响机理.结果表明:当润滑脂中添加的纳米氧化铈质量分数为0.8%时,表现出最佳的抗磨减摩性能,摩擦系数和磨斑直径相比原始润滑脂分别降低了22.5%和12.1%.三维形貌扫描发现钢球磨斑表面粗糙度相比原始润滑脂降低38.1%,平均磨斑高度与最大磨斑深度分别下降56.9%和51.3%,纳米氧化铈对磨损表面具有抛光和自修复作用.EDS和XPS的结果表明纳米氧化铈在钢球表面形成了1层润滑膜,减少了摩擦副之间的直接接触.

Comparative study on corrosion resistance and lubrication function of lithium complex grease and polyurea grease

In this study,lithium complex grease(LCG)and polyurea grease(PUG)were synthesized using mineral oil(500 SN)and polyalphaolefin(PAO40)as base oil,adsorbed onto lithium complex soap and polyurea as thickeners,respectively.The effects of grease formulation(thickener and base oil with different amounts(80,85,and 90 wt%)on the corrosion resistance and lubrication function were investigated in detail.The results have verified that the as-prepared greases have good anti-corrosion ability,ascribed to good salt-spray resistance and sealing function.Furthermore,the increase in the amount of base oil reduces the friction of the contact interface to some extent,whereas the wear resistance of these greases is not consistent with the friction reduction,because the thickener has a significant influence on the tribological property of greases,especially load-carrying capacity.PUG displays better physicochemical performance and lubrication function than LCG under the same conditions,mainly depending on the component/structure of polyurea thickener.The polyurea grease with 90 wt%PAO displays the best wear resistance owing to the synergistic lubrication of grease-film and tribochemical film,composed of Fe_(2)O_(3),FeO(OH),and nitrogen oxide.

Conductivity and tribological properties of IL-PANI/WS_(2) composite material in lithium complex grease

An ionic liquid-polyaniline/tungsten disulfide(IL-PANI/WS_(2))composite was synthesized in 1-butyl-3-methylimidazole tetrafluoroborate(LB104)aqueous solution by in-situ polymerization and characterized by Fourier transform infrared spectroscopy.A current-carrying friction and wear tester was used to study the tribological properties of steel-steel and copper-copper friction pairs lubricated by an IL-PANI/WS_(2) lithium complex grease(LCG).After the experiment,scanning electron microscope was used to observe the surface morphology of the wear scar on the steel and copper plates,and X-ray photoelectron spectrometer was used to analyze the elemental composition of the wear scar surface.The results show that compared with greases containing IL-PANI and WS_(2),greases containing IL-PANI/WS_(2) exhibit better antiwear performance when lubricating steel-steel friction pairs and better tribological performance and electrical conductivity when lubricating copper-copper friction pairs.Therefore,it can be concluded that WS_(2) and IL-PANI have a synergistic effect.

The rheological and tribological properties of calcium sulfonate complex greases

In this study,we synthesized two types of calcium sulfonate complex greases(barium soap and calcium soap)and investigated their physical,rheological,and tribological properties in detail.The test results showed that the evolution of their linear viscoelasticity functions with frequency were quite similar to those of traditional lubricating greases.Moreover,these two calcium sulfonate complex greases had good friction-reducing and antiwear properties at room temperature and at 150°C.In addition,by adding an organic molybdenum compound(MoDTC)to the base greases,we obtained a very low friction coefficient(0.065)for one of the greases(calcium soap)at 400 N and 500 N(maximum Hertzian pressures of 3.47 GPa and 3.74 GPa,respectively)at 150°C.X-ray photoelectron spectroscopy(XPS)analysis showed that the tribofilm was composed of some complex oxide species and CaCO3 that had formed on the worn surface.

基础油黏度对复合钛基润滑脂流变性能的影响

为了揭示基础油黏度对复合钛基润滑脂流变性能的影响规律,利用变化黏度的基础油制备了4种脂样,对各脂样的屈服极限、触变性能、剪切依时性进行了探讨。利用扫描电子显微镜表征了各脂样的皂纤维形貌,在稳态剪切条件下利用R/S+旋转流变仪测试了各脂样的流变参数。结果表明:各脂样的皂纤维形貌为团聚而又贯通的网络形态,基础油的黏度会对润滑脂的流变性能产生规律性的影响;基础油黏度增大后,皂纤维结构加粗,皂纤维间的空腔增大,导致脂样的屈服极限增大、触变能增大、黏度增大、抗剪切能力增强。

复合锂基润滑脂和脲基润滑脂成脂机理的差异

研究了炼制温度和反应方式对复合锂基润滑脂和脲基润滑脂滴点的影响,探讨了复合锂基润滑脂和脲基润滑脂成脂机理的异同,认为复合锂基润滑脂和脲基润滑脂形成高滴点的关键因素在于稠化剂分子间的缔合;脲基润滑脂稠化剂分子类型单一,更容易形成高滴点的润滑脂,而复合锂基润滑脂的稠化剂是由12-羟基硬脂酸锂和癸二酸双锂2种化合物相互缔合而成,如果在初始阶段2种化合物不发生彼此间的缔合,那么通过加热的方式不能将这种缔合方式转变为彼此间的缔合。均相反应是获得缔合型稠化剂的主要条件。

润滑脂组成对复合锂基润滑脂微观结构影响的研究

使用高分辨SEM观察锂基润滑脂的微观结构,对不同稠化剂、基础油黏度、添加剂对润滑脂的性能影响从微观结构的角度进行解释。结果表明,皂纤维的长度、粗细和缠绕程度形成的三维结构决定了润滑脂的胶体性能。在同等稠化剂含量下(质量分数12%),二组分癸羟型皂纤维三维结构比二组分硼羟型更为致密,三组分水杨酸型没有形成皂纤维结构,但滴点最高;高黏度基础油制备的润滑脂的皂纤维结构较低黏度基础油制备的润滑脂皂纤维结构疏松。在较少的含量情况下,添加剂的加入不影响皂纤维的大小和形状。

含纳米PTFE颗粒润滑脂的润滑性能研究

在四球摩擦磨损试验机上考察纳米PTFE颗粒作为添加剂对复合钛基润滑脂摩擦磨损性能的影响,采用扫描电子显微镜分析试验钢球磨斑的表面形貌,并利用X射线光电子能谱仪检测磨斑表面化学元素的组成及状态。结果表明,在一定添加量范围内,纳米PTFE可以改善复合钛基润滑脂的摩擦磨损性能,其中纳米PTFE质量分数为3%时,复合钛基润滑脂具有最佳的抗磨、减摩性能,可使摩擦因数、磨斑直径分别降低约25.4%和18.9%。纳米PTFE颗粒在钢球表面发生摩擦化学反应,生成了一层金属氟化物,有效地抑制了摩擦表面的黏着磨损和接触疲劳。

复合锂基润滑脂的流变特性与微观结构的关系研究

对5种复合锂基脂样品进行流变性测试,研究流变特征参数与样品的微观结构的关系。结果表明,复合锂基润滑脂的流变特性与体系的微观结构有关,其中流动转变指数可以描述润滑脂内部结构的破坏行为,其值越大,复合锂基脂的皂纤维结构越好;损耗系数小时复合锂基脂的脆性大,损耗系数大时复合锂基脂更容易铺展;在恒定剪切速率下,复合锂基脂的皂纤维结构越致密均匀,在剪切的过程中相对黏度下降率越小。通过测定润滑脂的流变特征参数,可以描述复合锂基润滑脂结构的稳定性和受破坏的程度,对于润滑脂的研发和使用有一定的指导意义。

复合锂基脂的研究

本文较详细地探讨了复合锂基脂的组成、制备条件及工艺、采用二组份复合或三组份复合时对复合锂基脂性能的影响。经详细的配方筛选和试验条件研究 ,研制的三组份复合锂基脂具有良好的高温多效性能 :高滴点 ,良好的胶体安定性、机械安定性、氧化安定性、防腐性、抗水性和润滑性。本文还考虑了几种添加剂对复合锂基脂性能的影响 :聚异丁烯可提高复合锂基脂的粘附性 :LaF3 、MCA可提高复合锂基脂的抗磨性

二乙基二硫代氨基甲酸镧配合物润滑脂添加剂的摩擦学研究

在空气环境下，制备了一种二乙基二硫代氨基甲酸与稀土元素镧的配合物（ＥＬａＤＴＣ）．利用四球试验机评价了其在通用锂基润滑脂中的极压和抗磨损性能，并与常用二烷基二硫代磷酸锌（ＺＤＤＰ）进行了对比．结果表明：此类稀土配合物能够显著提高锂基润滑脂的极压性能，且优于ＺＤＤＰ；同时具有良好的抗磨损性能，在添加质量分数为１％时ＥＬａＤＴＣ的抗磨损效果优于ＺＤＤＰ．采用ＸＰＳ对ＥＬａＤＴＣ的极压抗磨机理进行了分析，发现在摩擦过程中，添加于锂基脂中的二乙基二硫代氨基甲酸镧配合物与金属表面发生了摩擦化学反应，形成含有机氮、有机硫、硫酸盐和氧化镧等组分的复杂边界润滑膜，因而呈现出优良的极压抗磨性能．

二硫化钨超细粉末对高温复合锂基润滑脂性能的影响

研究新型润滑材料二硫化钨超细粉末(平均粒径小于500 nm)作为添加剂对高温复合锂基润滑脂性能的影响,并研制出一种二硫化钨高温润滑脂。经测试,该润滑脂具有高滴点、高油膜强度、低摩擦因数等良好性能,为充分利用我国丰富的钨资源提供一条新的出路。同时对二硫化钨超细粉末作为高温润滑脂添加剂的抗摩减磨作用机理进行分析,指出添加二硫化钨超细粉末的高温复合锂基润滑脂之所以具有这些优良的特性,是因为二硫化钨超细粉末具有易剪切、滑移的片层状结构特征,能产生沿弱结合面的剪切效应和微油池效应,在高温下还能在摩擦表面形成牢固的固体润滑转移膜和防止进一步氧化的致密氧化钨保护层。

酚类抗氧剂在润滑脂中的热稳定性及抗氧化性应用研究

文章采用压力差示扫描量热法(PDSC),分别以动态法和静态法两种方式,研究了加入3种典型的酚型抗氧剂T501、L135和L115后,复合锂基润滑脂氧化安定性的改善效果;以及不同的抗氧剂含量对复合锂基脂的氧化安定性的影响。结果表明:加入这3种抗氧剂后,复合锂基脂的起始氧化温度和氧化诱导时间均有不同程度的提高,其中加入硫代双酚型抗氧剂L115的抗氧化性能最佳;酯类单酚型抗氧剂L135次之;普通单酚型抗氧剂T501最差。热重分析(TG)结果表明,3种抗氧剂分子的热稳定性也遵从这一顺序,说明抗氧剂具有较好的热稳定性有助于在油脂中发挥更好的抗氧化性能。